Coal Age

AUG 2016

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38 www.coalage.com August 2016 ventilation Taking the Hard Line by donna schmidt, field editor Some elements of the underground mine, particularly those that are a per- manent fixture, tend to blend into the landscape over time. With little change to their design over the years and relatively low maintenance needs, ventilation in- frastructure could arguably be considered one of those components. That's not to say ventilation ducting hasn't evolved over time; original metal systems gave way to some use of flexible ducting in the 1970s, and since that time, flexible ducting has come to dominate the hard rock side of mining. Coal, with the need for greater volumes of air movement and heightened required safety require- ments, clung primarily to the rigid systems to get air to the face. Fiberglass has been an alternative option over the last couple of decades, though the cons of yet another form of rig- id infrastructure haven't gone away. While designed to have a smooth inner wall, al- lowing efficient air transport, the variable costs and the hazards of handling have created what many mines now consider just a necessary downside. Some say one can't get what they want without asking, and that is pre- cisely what several Quebec mines did in 2013, when they began seeking out someone to manufacture a product that would be easier to install, less expensive to ship than heavy, voluminous fiber- glass, repairable and more flexible. The ultimate result: Rigiflex plastic. Rigiflex became the basis for the Hard- line Performance Ducting line by Engi- neered Performance Ventilation System (EPVS), and the Canadian company went to work to develop a solution. Checking All the Boxes Absorbing feedback from the industry, Rigiflex was created to be flex- ible yet rigid with less energy needed to get air to where it's needed and greater space allowances underground, mean- ing less damage potential. A signifi- cant problem for conventional systems was also shipping, storage and place- ment of bulky ductwork. That, too, was specifically addressed by the EPVS team. "A copolymer was chosen versus PVC, as the cost was lower and standard formulations are lighter and somewhat flexible to resist damage in shipping and in placement and use in the mine," said Michael Schulte, mining engineer and president of Engineered Performance Ventilation Products. "The new copoly- mer also is about half the cost of stan- dard PVC formulations." The system comes in sheet form and can be constructed to spec at a ware- house or it can be built right where it will be needed underground. Once the Rigiflex is molded into 8-ft and 10-ft-wide sheets, those sheets are cut on a CNC machine and welded into round ducting. "The amazing part of the product is that we can put a round steel ring at each end and it keeps the product round, or we can put an oval ring at each end and the flexible plastic takes the oval form. The benefit of an oval product is that it gives more than 15% more headroom to pass, so there is less damage," Schulte pointed out. While there is no real limitation to ducting size, Saskatoon-headquartered EVPS, which has teamed up with Penn- sylvania-based Longwall Mining Services to expand the semirigid product into the coal space from the Appalachian region outward, said the most standard sizes for coal are emerging to be 16 in., 18 in., 20 in. and 24 in. due in part to air move- ment, but also to an average working space that is generally tighter than hard rock, where common sizes are 36 in., 42 in. and 48 in. "Hardline is seen as a replacement for rigid or semirigid ducting in all under- ground applications," LMS Owner John Whitfield said. "We are looking to make Hardline the 'new normal' for mines as the resistance to airflow is less than for steel and fiberglass, leading to lower energy use. Even though we are closely related to ener- gy generation in the coal industry, we need to be conscious of the high energy use of mines in a time when some areas have a The standard sizes of the semirigid Hardline for coal applications include 16 in., 18 in., 20 in. and 24 in. The potential for flexible ventilation systems as a next generation of underground infrastructure

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